The present invention relates.to extractors for removing broken threaded fasteners such as broken bolts, and more particularly to a broken bolt extractor combined with a drill head in a single combination tool.
Conventional easy-out type bolt extractors for extracting broken bolts within a threaded bore normally are formed of a pointed tool having gripping teeth or shaped flutes adpated to engage the sides of a bore drilled through the broken bolt. The gripping surfaces are shaped to engage the bore when the extractor is rotated in a direction opposite that of the bolt threads so that rotation of the extractor unthreads the broken bolt and removes it from the threaded bore. These extractors require that a hole first be drilled through the broken bolt prior to the insertion of the bolt extractor within the bolt. One of the shortcomings of these tools is that the drill bit is often broken in the process of drilling which results in a compound problem of removal, requiring removal of both the broken bolt and the broken drill bit. Even when the drill bit is not broken, it often drives the bolt deeper into the threaded hole making extraction more difficult. This process requires that the drill bit be removed before inserting the bolt extractor so that at least three separate operations are needed, namely, drilling of a bore within the broken bolt, removing of the drill bit, and inserting the extractor and extracting the bolt.
With the present invention, the drill bit and the bolt extractor are combined in a single tool. The lower surface of the tool is provided with the drill bit which has a cutting edge with a pitch in the direction opposite to the threads of the bolt bore. A bolt extractor is reciprocally mounted on the drill bit shaft above the drill bit. The top of the tool includes a drive head which is adapted to coact with a power or hand drill or other suitable driving means. The lower end of the drive head includes a coupling means which contacts a mating pottion on the top of the reciprocally moveable bolt extractor in order to engage the bolt extractor with the drive head after the tool has been drilled a predetermined length into the broken bolt. Once the bolt extractor is engaged with the drive head, the extractor then proceeds to grip the inside of the drilled out bore to enable the broken bolt to be extracted.
Among the objects of the present invention are the provision of a threaded fastener extractor tool which is combined with a drilling bit so that a broken bolt may be removed in a single operation.